Grade 3: The Skeletal System - Where Tomorrow Begins

Grade 3: The Skeletal System

Lesson 1: Bone Identification Lesson 2: How Do Bones Feel and Look? Lesson 3: Why Are Bones Hard? Lesson 4: Joints

(Note to teachers: This unit is long, but can easily be broken down into separate segments according to the lesson number.)

Objectives: 1. Students will identify at least three functions of the Skeletal System. 2. Students will know the technical names of the major bones in the Skeletal System. 3. Students will explore the shapes and physical characteristics of bones, naming the four major shapes of bone. 4. Students will discover that calcium supports strong, healthy bones and that bones are alive, growing and changing throughout life. 5. Students will name the three types of joints, demonstrate how joints allow us to move, and identify that different joints perform different functions.

Materials: ? Skeleton Model (optional) ? Crayons or colored pencils ? Butcher paper ? Masking tape ? Marking pens ? Chicken bones ? Vinegar ? Plastic containers ? Small plastic toy animals ? Bones (skeleton model, if available) ? Peanut M&M's ? Books (from the book list or others that seem appropriate) ? Kitchen utensils (egg beater, can opener) ? Overhead projector ? Overhead projector film/markers ? Bone/Technical Name/Purpose handout (See Figure 1) ? Cards with Bone Names (See Figure 2) ? Pictures of each part of the skeleton drawn on separate pieces of paper ("Be a Bone" Exercise) (See Figure 3) ? Student Skeleton Puzzle (See Figure 4) ? Skeleton Information Chart (See Figure 5) ? School House Rock ? Science Rock (See Figure 6) ? Detailed Skeleton Picture (See Figure 7)

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? "Drink Milk" advertisement (See Figure 8) ? Parent Letter (See Figure 9) ? Parent Letter ? Reminder (See Figure 10) ? Large Skeleton Puzzle (See Figure 11) ? Joint Information Chart (See Figure 12)

Activity Summary: Students will acquire a basic understanding of the Skeletal System, bones, and joints, and relate this information to their own bodies.

Background Information for the Teacher:

? The Skeletal System is made up of the bones of the body and the joints between the bones, as well as certain connective tissue (cartilage and ligaments.) This lesson will focus on the bones and joints. The skeleton is the internal framework of the body. Bones are probably best known for the hard structural role they play in the human body, but in fact bones are living tissue. Because bone is live tissue it receives nutrients and oxygen from the blood vessels that supply the bone. In addition, bones have nerves. That is why when you hit your "funny" bone in your elbow it doesn't feel very funny.

? Bones come in four basic shapes: LONG, FLAT, SHORT and IRREGULAR.

? Bones also vary in texture: they may be either rough or smooth, with projections and hollows. Places on the bones that have irregular shapesand textures are the attachment sites for the muscles.

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The SKELETON has many important functions in the body. It provides:

? SUPPORT for the body ? The hardness of the bones provides a strong framework the helps us stand upright, and anchors muscles and organs.

? PROTECTION of the internal body organs ? The ribs protect the heart, lungs, kidneys, and liver; the vertebral column surrounds the spinal cord. The hip bones give support and some protection to the bladder and the female reproductive organs. The skull encases the brain.

? MOVEMENT of the body ? All muscles in the body attach to bones and all muscles cross joints. Muscles connect one bone with another bone. When the muscles move (contract) the joint moves and the bones that make up the joint move closer together.

? STORAGE of minerals and fat ? Calcium, magnesium, phosphorous and sodium are stored in the bones.

? RED BLOOD CELL FORMATION ? The red marrow found in the internal cavity of some bones is responsible for producing red blood cells.

The SKELETON has 206 bones. The major skeletal regions are:

? SKULL: Made up of more than 20 different bones of the cranium, face and ear. The smallest bones in the body, the auditory ossicles, are located in the ear.

? SPINE: Consists of a column of 26 bones, 24 of which are called vertebrae: cervical (7); thoracic (12); and lumbar (5). The sacrum and the coccyx are made up of four or five vertebrae fused together.

? RIBS & STERNUM (BREASTBONE): 25 bones (12 pairs of ribs, plus the sternum)

? PELVIS (HIP BONES), LEGS, and FEET: 62 bones. The longest bone in the body is the FEMUR (thigh bone)

BONE FORMATION & GROWTH

Bones grow, change and regenerate throughout life. This is a dynamic (not static) process that starts before birth and continues throughout a person's life. Bone begins as cartilage before birth, as the fetus begins the process of turning cartilage into bone (ossification.) Calcium is collected in the bony material along with other minerals and this facilitates the ossification process. By the time a baby is born, most of the cartilage has formed into bone.

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During childhood, the long bones (such as the thighbone, shin bone, and long bones of the arm) lengthen and harden. This occurs through a process called bone remodeling. As a child's body grows, bone remodeling transports bone material throughout the body in order to maintain vital calcium levels in the blood, in addition to the calcium needed for bone growth. Calcium is so important to the body that if there is not enough of it in the blood, hormones will break down calcium from bony tissue and re-distribute it to other sites in the body. Children have a greater need for calcium in order to develop the larger, denser, longer and stronger bones they need to grow into adolescence and adulthood.

JOINTS

A joint is where two bones meet. Bones are hard and can't bend, twist or turn, but joints can do all those things. Muscles always cross joints. Most muscles cross only one joint, but a few muscles cross two joints.

There are three kinds of joints:

1. Nearly immoveable ? such as the joints, or sutures, of the skull bones;

2. Slightly moveable ? such as joints of the hip bones; and

3. Freely moveable ? such as the knees, shoulders, wrists and toes. These are the most common joints in the body.

There are also three kinds of joint movement:

1. Pivot ? One bone joint rotates around another bone. (Example: the movement of the head when a person is looking from side to side.)

2. Ball and socket ? The end of one bone has a ball shape to it. It fits into the end of another bone that has a round hollow in it that looks like a cup. (Examples: the shoulder joint and the hip joint are both ball and socket joints. This joint allows omni-directional movement.)

3. Hinge ? The rounded end of one bone is rounded and fits into a depression in the other bone. The movement of this joint is like a door hinge, thus the name. (Examples: In the elbow and knee joints the hinge joint movement is in one direction and moves the bones closer together (flexion) and farther apart (extension.)

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VOCABULARY:

? Skeletal System ? made up of the bones in the body, the joints between the bones, and connective tissue (such as cartilage and ligaments)

? Skeleton ? the internal framework of the body

? Bone ?living tissue made up of bone cells and minerals, including calcium. Bones have many shapes and sizes and are the individual components of the skeleton

? Joint ?where two bones come together

LESSON 1: Bone Identification

Engage (5 minutes): Have the students take out a piece of paper and write their names on the top, numbering to two.

1. Ask: "How many bones do you have in your body?" (Have the students write down an estimate.)

2. After everyone has written a number down, show the students a jar in which you've put 206 Peanut M&M's. Say: "The number of Peanut M&M's in this jar is THE SAME as the number of bones in your body. Estimate how many bones you think there are in your body and how many peanut M&M's are in the jar." (Let the students share their estimates, then share the correct answer--206.)

3. Say: "Where are our bones? Are we able to see our bones?" (No. Bones are INSIDE your body.)

4. Say: "Bones are the internal FRAMEWORK of the body, which is the SKELETON. Think of a bed. If we took all the padding and fabric away what would the `internal frame' consist of?" (Wires, boards, etc...) "Just like the body, if we take all the outside `stuff' away, the inside frame is the bones."

Explore (15 minutes):

1. Divide the students into groups of three or four and assign roles: Recorder, Reporter, and Supply Manager.

2. Give each group a sheet of paper with a graphic organizer or have them copy it from the board. (See Figure 1)

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